NASA astronaut Michael Foale and Russian cosmonaut Alexander Kaleri celebrated New Year's Day on the space station, then were notified Monday that the air pressure was slowly dropping.

By Marcia Dunn Aerospace Writer The Associated Press

Updated: 1:05 p.m. ET Jan. 09, 2004CAPE CANAVERAL, Fla. - An air purifier that was the prime suspect for a cabin leak at the international space station turned out to be airtight Friday as the crew widened the search for the mystery leak.

The cabin pressure continued to slowly fall as flight controllers in both the United States and Russian debated what to do next. One plan, not yet finalized, would have the two men on board, Russian cosmonaut Alexander Kaleri and NASA astronaut Michael Foale, closing the hatches on individual compartments one at a time in an attempt to isolate any potential leaks.

Mission Control stressed that even though the pressure was now down to 14.0 pounds per square inch, it was still safe for the crew and station operations. The threshold, however, for equipment failure  not all equipment, just some  is 13.9 pounds per square inch.

The normal air pressure aboard the space station is 14.7 pounds per square inch, a level not present up there since before Christmas.

Checking equipment

Flight controllers zeroed in on the Russian carbon-dioxide removal unit earlier this week as the source of the pressure decay, but Kaleri found nothing wrong with it Friday. The system was more or less reported to be airtight, Mission Control reported.

Kaleri checked other environmental systems on the Russian side of the space station and nothing was found to be leaking.

The next step, probably this weekend, will have Kaleri and Foale sealing off the docked Russian cargo ship and then the Russian air lock and then the American air lock, to gauge any pressure changes.

Space station managers are meticulously going through the list of equipment that is susceptible to falling pressure, Mission Control said. Its possible that the main item in question  a monitor for air contaminants  could be simply turned off in order to preserve it once the pressure reached 13.9 pounds per square inch.

Engineers do not believe a repressurization would be necessary before Sunday or Monday.

No immediate danger

In emphasizing the lack of immediate danger, Mission Control noted that the current level of 14 pounds per square inch is equivalent to the atmospheric pressure in Oklahoma City. There are plenty of places on Earth where people live with much lower air pressure, Mission Control said, citing Las Vegas at 13.6 pounds per square inch, Denver at just over 12 pounds per square inch, and Mexico City at less than 12 pounds per square inch.

Foale, the commander, and Kaleri are supposed to remain on board until the end of April. They arrived in October as the eighth set of full-time residents.

NASA has reduced the number of space station residents from three to two for the foreseeable future because of the grounding of the shuttle fleet in the wake of the Columbia disaster. Russian spacecraft are simply too small to deliver all the necessary supplies and spare parts.

OK, here's the theory: The universe is not only expanding, everything in it is expanding too. Ergo, the space station is expanding which causes the air pressure to drop. Either that or President Bush is stealing the air to kill these guys and cause pain for their families/children.

OK, here is what I did. Rule of thumb is one inch of Mercury for each 1000' in altitude. At 2000' that would be 27.92. That converts to 13.7psi. So 2124' would be close to 13.6. BTW, that is what it is called on the ref desk: Convert Anything (on the left side of the page). Great site.

The Apollo era also used a pure oxygen atmosphere. That is what caused severity of the capsule fire in the Apollo 1 test, however that was at a 1 atm internal pressure (14.7 psia, which may not to healthy as well, outside of fire considerations). (Question to freepers who may have worked on Apollo: after the fire did NASA go to an N2/O2 atmosphere in the command module at 14.7 psia, changing to 5 psia pure oxygen somewhere in the flight profile?). I suspect that the ISS has an N2/O2 atmosphere. Could be wrong. Another consideration for the air pressure, since equipment operation was mentioned, is heat conduction, although fans may be needed. Insufficient air density results in less heat carryoff. I have seen power transformers de-rated for high elevation (starting at 4000 feet). Another DUMB question for any aerospace freepers - Can there be convective cooling in a zero-gee enviroment, or are circulation fans needed.

8 - Thanks for the ping. What I do know, is that they are running out of pressure pretty fast. A few more weeks. They NASA, better get off their butts and do something - fast, or they will be abandoning ship.

this is ridiculous, that they don't have a plan, for something as simple and predictable as a leak, and closing off the compartment hatches. MY GOODNESS, THEY ARE STOOOPID!!! Two weeks of leaking and they don't even have a plan yet? A plan they should have had before the first launch? Shades of o-rings and falling off foam.

Everybody, cover your heads, and duck !!!!

quote:

"The cabin pressure continued to slowly fall as flight controllers in both the United States and Russian debated what to do next. One plan, not yet finalized, would have the two men on board, Russian cosmonaut Alexander Kaleri and NASA astronaut Michael Foale, closing the hatches on individual compartments one at a time in an attempt to isolate any potential leaks.

Mission Control stressed that even though the pressure was now down to 14.0 pounds per square inch, it was still safe for the crew and station operations. The threshold, however, for equipment failure  not all equipment, just some  is 13.9 pounds per square inch."

XBob said: "This is ridiculous, that they don't have a plan, for something as simple and predictable as a leak, and closing off the compartment hatches. "

It doesn't seem to make sense, does it?

Sealing the compartments would allow for eliminating many systems as the possible cause.

Additionally, while waiting until the proper time to repair the leak, it might be possible to pump atmosphere from the leaky compartment to the others. One could raise the pressure in the non-leaky areas, lower it substantially in the leaky area, and thus reduce considerably the amount of air lost to the leak.

If access to the leaky compartment was not needed often, it might be possible to extend by an order of magnitude or more the amount of time available to fix the leak.

Also, there is little mention of a reserve supply of atmosphere. I would think that pressurized tanks could have been used to store spare air and these tanks could be re-supplied periodically. After all, if you run out of air, what need is there of anything else?

Are there any Freepers who can supply an explanation for what we see happening?

Dog Gone said: "Stick it in a bathtub, and see where the bubbles come out."

Of course, if they allow very much more leakage, then there will be no bubbles coming out. They will have to look for water spraying in. (Lots of assumptions regarding the tub and its environs.)

Good point about the reliability of the instrumentation. Perhaps they are seeing the result of a corroding electrical connection. How much of this stuff was purchased from the lowest bidder ( our system ) or manufactured by slave ( socialist ) labor?

Seems like FIRST thing to do would be to isolate each compartment - THAT immediately tells which eqpt''s it CAN'T be.

Sure, an "outside" bubble check isn't practical - can't "paintbrush" soapy water solution in a vacuum, best I can tell, even if it could be done to coat the whole exterior of the thing coating every joint.

But an outside IR camera, aimed back at the single compartment in darkness, should reveal a "trail" of gasses from one or more joints or seals or connections.

And are you sure you want to randomly "paint (er, contaminate with water) joints designed to be pure and pristine in a space environment?

41
posted on 01/09/2004 8:56:40 PM PST
by Robert A. Cook, PE
(I can only support FR by donating monthly, but ABBCNNBCBS continue to lie every day!)

41 - I was responding to the 'closing off compartments' - I guess I should have specified. The 'soapy water' leak detection is a dumb idea. Simply save air and at the same time narrow down the search by compartment - step one in emergency procedures.

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